Fractal character of triglyceride spherulites is a consequence of nucleation kinetics

Marangoni, Alejandro G.; Ollivon, Michel

doi:10.1016/j.cplett.2007.05.098

Cited by 29 publications

(24 citation statements)

References 19 publications

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“…When applying Avrami's approximate equation to a supramolecular material which is building up a fractal fibrous network during gelation, they could show that the exponent is related to the fractal dimension of branching events. Marangoni and Ollivon [21] presented the fractal nature of TAG spherulites due to nucleation kinetics in a non crystallizing diluent.…”

Section: Introductionmentioning

confidence: 99%

Crystallization Kinetics of Cocoa Fat Systems: Experiments and Modeling

Padar

Jeelani

Windhab

2008

J Americ Oil Chem Soc

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Isothermal crystallization kinetics of unseeded and seeded cocoa butter and milk chocolate is experimentally investigated under quiescent conditions at different temperatures in terms of the temporal increase in the solid fat content. The theoretical equations of Avrami based on one-, two-and three-dimensional crystal growth are tested with the experimental data. The equation for onedimensional crystal growth represents well the kinetics of unseeded cocoa butter crystallization of form a and b 0 . This is also true for cocoa butter crystal seeded milk chocolate. The sterical hindrance due to high solids content in chocolate restricts crystallization to lineal growth. In contrast, the equation for two-dimensional crystal growth fits best the seeded cocoa butter crystallization kinetics. However, a transition from three-to one-dimensional growth kinetics seems to occur. Published data on crystallization of a single component involving spherulite crystals are represented well by Avrami's three-dimensional theoretical equation. The theoretical equations enable the determination of the fundamental crystallization parameters such as the probability of nucleation and the number density of nuclei based on the measured crystal growth rate. This is not possible with Avrami's approximate equation although it fits the experimental data well. The crystallization can be reasonably well defined for single component systems. However, there is no model which fits the multicomponent crystallization processes as observed in fat systems. List of symbols k rate constant in Avrami approximate equation (s -m ) m exponent in Avrami approximate equation N number of germ nuclei per unit volume at any instant of time (m -3 ) N 0 initial number of germ nuclei per unit volume (m -3 ) p probability of growth of germ nuclei per unit time (s -1 ) l length or radius of crystal grain (m) _ l average rate of growth of length or radius of crystal grain (m s -1 ) S mass of crystalline phase per unit mass of lipid phase S m maximum mass of crystalline phase per unit mass of lipid phase S m0 fraction of solid fat at the beginning of bulk crystallization t time (s) T temperature (K) v volume of crystal grain (m 3 ) V volume of crystalline phase per unit volume of suspension V m maximum volume of crystalline phase per unit volume of suspension V e volume of crystal grains per unit volume of suspension formed without growth impediment z dimensionless re-scaled timeGreek letters _ c shear rate (s -1 ) r 1 cross-sectional area of rod-like crystal (m 2 ) r 2 thickness of plate-like crystal (m)

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Section: Introductionmentioning

confidence: 99%

Crystallization Kinetics of Cocoa Fat Systems: Experiments and Modeling

Padar

Jeelani

Windhab

2008

J Americ Oil Chem Soc

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“…They have an envelope roughly spherical in three dimensions (or circular in two dimensions, still retaining the name spherulite). These morphologies were observed in a broad range of materials, including pure Se; [84] oxid and metallic glasses; minerals; [88] polymers; [89] liquid crystals; [90,91] simple organic liquids; [79] fats; [92] and systems of diverse biological molecules. [93][94][95][96] Spherulitic structures were also implicated in various human diseases such as Alzheimer's, type II diabetes, and other protein aggregation diseases.…”

Section: Disordered (''Dizzy'') Dendrites: Particles Vs M Hmentioning

confidence: 99%

Phase-Field Modeling of Polycrystalline Solidification: From Needle Crystals to Spherulites—A Review

Gránásy

Rátkai

Szàllàs

et al. 2013

Metall Mater Trans A

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LÁ SZLÓ GRÁ NÁ SY, LÁ SZLÓ RÁ TKAI, ATTILA SZÁ LLÁ S, BÁ LINT KORBULY, GYULA I. TÓ TH, LÁ SZLÓ KÖ RNYEI, and TAMÁ S PUSZTAI Advances in the orientation-field-based phase-field (PF) models made in the past are reviewed. The models applied incorporate homogeneous and heterogeneous nucleation of growth centers and several mechanisms to form new grains at the perimeter of growing crystals, a phenomenon termed growth front nucleation. Examples for PF modeling of such complex polycrystalline structures are shown as impinging symmetric dendrites, polycrystalline growth forms (ranging from disordered dendrites to spherulitic patterns), and various eutectic structures, including spiraling two-phase dendrites. Simulations exploring possible control of solidification patterns in thin films via external fields, confined geometry, particle additives, scratching/piercing the films, etc. are also displayed. Advantages, problems, and possible solutions associated with quantitative PF simulations are discussed briefly.

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“…The term polymorphism describes the type of lateral packing of the aliphatic triglyceride chains [38]. The lateral packing is influenced by factors such as cooling rate, agitation temperature, and the mechanical treatment [11,14,18,41].…”

Section: Resultsmentioning

confidence: 99%